Microphone



BERLINER, phone.

No. 225,790. Patented Mar. 23, 188.0.

NITED STATES PATENT OFFICE.

EMILE BERLLNER, OF BOSTON, MASSACHUSETTS.

MICROPHONE.

SPECIFICATION formingpart of Letters Patent No. 225,790, dated March 23,1880.

Application filed November 12, 1879. V

To all whom it may concern:

Be it known that I, EMILE BERLINER, of Boston, in the county of Suffolkand State of Massachusetts, have invented a new and useful Improvementin Microphones, of which the following is a specification, referencebeing had to the accompanying drawings.

In an application for Letters Patent of the United States filedSeptember 5, 1879, I have described a microphone in which the twoelectrodes are maintained in contact with each other by the action ofgravity, and one of the electrodes slides toward the other in aninclined support.

The first part of the present invention is an improvement upon themicrophone described in said application; and it consists of amicrophone in which the contact between the two electrodes is variedduring the transmission of sounds by the variation in the pressurebetween the two electrodes caused by the pressure of a pendulous weightsuspended in such a manner that it is kept from reaching its point ofrest by the interposition of the electrodes, one of which may beattached to the weight.

It also consists in suspending this weight by a band or ribbon of someflexible material, whereby the suspended electrode is prevented frommoving from side to side on the fixed electrode, and thus causing animperfect transmission of sounds.

In the accompanying drawings, Figure 1 is a view in elevation of amicrophone constructed according to the principle of my invention, andFig. 2 is a sectional view of the same. Figs. 3 and 4. are views ofother forms of microphone embodying the principle of my invention, andFig. 5 is a view in section of my improved damper.

In these several figures the same letters refer to the same parts.

The microphone which is represented in Figs. 1 and 2, and which iseasily and cheaply made, and is efficient in action, is constructed asfollows: A is the diaphragm for receiving the sound-waves, whichdiaphragm is supported in the usual manner; and B is a block of hardenedcarbon, having a smooth surface, which is in a plane parallel to theplane of the diaphragm, and which block is attached to the center of thediaphragm, and forms one of the electrodes. The other electrode consistsof a piece of hardened carbon, C, fixed in a cylinder of metal, D, whichcylinder has a plate of metal, E, attached to it by the screw F, or inany other suitable manner.

G is a plate of metal, which is attached at one end to the diaphragm Aby means of a suitable insulated screw, and is inclined outward; and tothis plate G, near the screw H, is attached one end of a ribbon or band,I, of some flexible conducting material, such as metallic foil, or ametallic web of cloth, paper, or some similar flexible substancemetallized or otherwise rendered conducting, which band or ribbon isattached at its other end to the plate E, which rests upon the end ofthe plate G.

The cylinder D and strip I thus form a pendulum, which has its point ofsuspension above the carbon block B, and is prevented from reaching itspoint of rest by the contact of the carbon piece 0 with the carbon blockB, and consequently bears upon the face of the said block with a forceproportional to the weight of the cylinder D and the distance of thecenter of gravity of the pendulum from its point of rest. Thismicrophone can therefore be adjusted to any desired degree ofsensibility, either by varying the weight of the cylinder by varying thedistance of the surface of the carbon block B from the surface of thediaphragm, so as to increase the inclination of the pendulum, or byadjusting a movable weight on the cylinder in such a manner as to varythe distance of the center of gravity of the pendulum from the surfaceof the carbon block B, and this weight may be the screw F.

It is important in a microphone, in order to insure the cleartransmission of sounds, especially of articulate sounds, that thesuspended electrode should be prey'ented from moving from side to sideon the fixed electrode; and I obtain this result in the presentinvention by the use of the ribbon or band I for supporting the weightD, whereby the carbon piece 0 is prevented from moving from side to sideon the surface of the carbon block B. The support 1 afforded to theplate E by the end of the plate G also contributes to this result.

The electrodes B and 0 maybe made of any conducting substance.

Fig. 3 represents a form of microphone in which one of the electrodes,0, is made of platinum, and is attached to a light metallic spring, a,which forms part of the circuit. In this case the pendulous weight restsupon the electrode (J, and the band or ribbon need not be a conductor.

Fig. 4 shows another form of microphone, in which the transmissionofsounds is obtained by the variations in pressure upon a button offinely-divided carbon. In this case, also, the ribbon or band I need notbe a conductor.

The improved damper is shown at Fig. 4, and consists of a ring of softrubber or other similar elastic substance inserted between the diaphragmand the head of the screwK which secures the diaphragm to the support A.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. A contact telephone or microphone con sisting of two electrodes of anelectric current in contact with one another, which contact is variedduring the transmission of sounds by the variation in the pressure uponsaid contact of a pendulous weight, which is kept out of its point ofrest by the interposition of said electrodes, substantially as and forthe purpose set forth.

2. A contact telephone or microphone in which one electrode forms partof a pendulum which is kept out of its point of rest by the contact ofsaid electrode with the opposite electrode, thereby producing pressureat the contact between the said electrodes, substantially as and for thepurpose set forth.

3. In a contact telephone or microphone having no frictional. or rubbingelectric contact, and provided with a diaphragm and a damping device formodifying the vibration of the diaphragm a suspended weight affectingthe electrical contact between the electrodes in contact with oneanother, said weight being held in position from at least two points,which are situated on opposite sides of the center of gravity of saidweight, substantially as and for the purpose set forth.

4. In a contact telephone or microphone, the combination ot'a vibratingsurface forming one pole of an electric current, a pendulous weightforming the opposite pole, and a band or ribbon of flexible materialsuspending the said weight, which band or ribbon may or may not be aconductor, substantially as and for the purpose set forth. 7

5. In acontact telephone or microphone, the combination of a band orribbon of metallic foil or its equivalent and an electrode suspendedtherefrom, substantially as and for the purpose set forth.

6. In a contact telephone or microphone, the combination of the flexibleband I and the supporting-plate G, substantially as and for the purposeset forth.

7. In a contact telephone or microphone, the combination'of thediaphragm A, carbon block B, carbon piece 0, adjustable weight D, plateE, flexible band or ribbon I, and supportingplate G, substantially asand for the purpose set forth.

In witness whereof I have hereunto set my hand in presence of thesubscribing witnesses.

EMILE BERLINER.

IVitnesses:

CHARLES E. BURLINGAME, ALEX. L. HAYES.

